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Biomedical subjects

E Yelverton

Publications and source records attributed to E Yelverton.

10 recordsLinked to original sources
PubMed1994

The function of a ribosomal frameshifting signal from human immunodeficiency virus-1 in Escherichia coli.

A 15-17 nucleotide sequence from the gag-pol ribosome frameshift site of HIV-1 directs analogous ribosomal frameshifting in Escherichia coli. Limitation for leucine, which is encoded precisely at the frameshift site, dramatically increased the frequency of leftward frameshifting. Limitation for phenylalanine or arginine, which are encoded just before and just after the frameshift, did not significantly affect frameshifting. Protein sequence analysis demonstrated the occurrence of two closely related frameshift mechanisms. In the first, ribosomes appear to bind leucyl-tRNA at the frameshift site and then slip leftward. This is the 'simultaneous slippage' mechanism. In the second, ribosomes appear to slip before binding aminoacyl-tRNA, and then bind phenylalanyl-tRNA, which is encoded in the left-shifted reading frame. This mechanism is identical to the 'overlapping reading' we have demonstrated at other bacterial frameshift sites. The HIV-1 sequence is prone to frame-shifting by both mechanisms in E. coli.

Amino Acid Sequence↗
PubMed1983

Rabies virus glycoprotein analogs: biosynthesis in Escherichia coli.

The surface of rabies virus is composed of an approximately 60,000 dalton glycoprotein, in which most of the antigenic and immunogenic determinants of the virus reside. We have constructed plasmids for the direct expression in Escherichia coli of the mature full length rabies glycoprotein gene and also for the expression of a glycoprotein gene which has been truncated to exclude the coding region for a hydrophobic, possibly transmembrane, domain of the protein. Escherichia coli harboring the plasmids synthesize analog proteins which conform by several biochemical and antigenic criteria to rabies glycoprotein.

Amino Acid Sequence↗
PubMed1982

Increased synthesis in E. coli of fibroblast and leukocyte interferons through alterations in ribosome binding sites.

Eleven chimeric plasmids have been constructed which direct the synthesis of mature human fibroblast (IFN-beta 1) or leukocyte interferon (IFN-alpha A) proteins under the control of the E. coli trp promoter. The plasmids differ with respect to the nucleotide spacing between the Shine-Dalgarno sequence of the trp leader and the ATG translation start signal of the interferon genes. By utilizing a unique Xba I endonuclease site located within the spacer region of the expression plasmids, the spacings were altered from 2-10 nucleotides or 7-15 nucleotides for the fibroblast and leukocyte interferon expression plasmids, respectively. The optimal spacing for expression, as determined by interferon assay, is 9 nucleotides for both types of transcripts, despite differences in nucleotide sequence within the spacer region and downstream from the AUG initiator. Yields of IFN-alpha A varied about six-fold, while among the different IFN-beta 1 expression plasmids a range of more than 100-fold in interferon production was observed. The difference in the range of variation between the IFN-alpha A and IFN-beta 1 plasmids is attributed partly to changes in messenger RNA secondary structure within the ribosome binding sites which affect message half-life.

Binding Sites↗
PubMed1981

The structure of eight distinct cloned human leukocyte interferon cDNAs.

Eight classes of human leukocyte interferon (LeIFN) cDNA clones have been identified in a cDNA library prepared from a myeloblastoid cell line. The nucleotide sequences demonstrate that the multiple human LeIFN genes code for a family of homologous, yet distinct proteins. One of the cDNA clones may have been derived from the transcription of a LeIFN pseudogene.

Amino Acid Sequence↗
PubMed1981

Bacterial synthesis of a novel human leukocyte interferon.

A novel human leukocyte interferon cDNA clone (LeIF B) was identified in a cDNA library prepared using polyadenylated mRNA of a myeloblastoid cell line. The nucleotide sequence of LeIF B differs significantly from other published leukocyte interferon cDNA sequences. An expression plasmid was constructed which directs the synthesis in E. coli of 8 x 10(7) interferon units per liter of culture. LeIF B exhibits markedly different specificities from another bacterially synthesized human leukocyte interferon, LeIF A.

Base Sequence↗
PubMed1980

Human leukocyte interferon produced by E. coli is biologically active.

A human leukocyte interferon cDNA was enzymatically synthesized, inserted into the vector pBR322, and cloned in Escherichia coli. The DNA sequence codes for a 23-amino acid signal peptide followed by an interferon polypeptide of 165 amino acids. An expression plasmid was constructed which permits the synthesis in E. coli of 2.5 x 10(8) units of interferon per litre of culture. This LeIF protected squirrel monkeys from lethal encephalomyocarditis virus infection.

Amino Acid Sequence↗
PubMed1980

Synthesis of human fibroblast interferon by E. coli.

A cDNA library was constructed using mRNA from human fibroblasts induced with poly(I):poly(C). A bacterial clone containing fibroblast interferon cDNA sequences was identified by hybridization to a cDNA probe synthesized using deoxyoligonucleotide primers which hybridize to fibroblast interferon mRNA specifically. Expression plasmids were constructed which permitted the synthesis in E. coli of 8 x 10(7) units of human fibroblast interferon per liter of culture. The bacterially produced fibroblast interferon is indistinguishable from authentic human fibroblast interferon by several criteria.

Amino Acid Sequence↗